The present invention relates to a navigation method for precisely steering a flying object employing a transit time measurement and ascertaining a deviation of the flying object from a given or predetermined rated flight path or course.
Methods and devices for guiding a flying object along a predetermined course are well known in the art in many modifications. Thus, German Patent Publication (DOS) No. 2,624,821 discloses a method for guiding a flying object whereby the flying object takes a bearing relative to at least one marking on the landing surface. With the aid of such bearing taking the elevation and azimuth direction is measured. The resulting measured values are compared with given rated values relating to the landing surface. The comparing result is then used for the steering or guiding. This prior art system requires a substantial equipment expense and in addition it has the disadvantage that the flying object itself constitutes an easy target because the flying object carries pulse transmitters.
Another prior art trajectory guiding system operates in accordance with the so-called radio guidance beam. In this system the position of the aircraft or flying object relative to a radio guide beam transmitter is provided in the form of a signal representing the elevation and/or azimuth and the angular distance and such signal is received by an airborne radio beam receiver which cooperates with an analog or digital computer. The computer multiplies angular deviating signals with the angular distance or so-called slant distance or with a function of the slant distance. The angular deviation is determined relative to a straight flight path or trajectory or relative to a curved trajectory. The just mentioned prior art method intends to eliminate instabilities in the approach paths or approach profiles. However, even in this method the entire system is technically involved, and hence rather expensive. Besides, an independent approach of the landing area by the flying object is not possible in this system. Stated differently, the flying object depends on the equipment of the ground based guiding system and must operate in synchronism with the ground guiding system.
German Patent Publication (DOS) No. 2,424,159 discloses a system for guiding aircraft along an angular coordinate of a ground station. This system comprises a measuring circuit for ascertaining the angular coordinates of each aircraft by processing the signals received from an approaching aircraft. The system includes a transmitter for transmitting the signals resulting from the measurements. The transmitter includes equipment for transmitting a variable address signal which is coordinated with a binary code flagging sign signifying the words "assigned" and "available". This known system is intended to solve the problem of the so-called "take-over" of aircrafts by the control tower. However, this system also does not permit an independent approach by the aircraft. In addition, the aircraft or flying object is again an easy target because of its transmitter activity.